Kumamoto andesite

Rock studied is Kumamoto andesite, JAPAN. The rock-forming minerals of this rock are plagioclase, pyroxene, hornblende and so on. Some phenocrysts of about 3 mm length are distributed in groundmass. 

K/-V relations observed in this study are shown in Figure 3, where results obtained under two different water vapor pressures were shown. It can be seen that the reproducibility of testing results of Kumamoto andesite under the same environmental condition is very high from this figure. In addition, it can be seen that the crack growth behaviors are facilitated under high water vapor pressure. This is in harmony with the theory of stress corrosion cracking in rocks. The obtained results are summarized in Table 1, where K/ means K, at V = 10 [m/s], and v means v at Ki = 1.6 [MN/m ]. Ki and v were determined in order to compare the stress intensity factor... 

Krv relations obtained in this study show that the crack growth behavior in andesite is promoted by water vapor under air condition. These are consistent with the results of uniaxial compression tests and Brazilian tests by Jeong et al. (2003), in which the strengths of Kumamoto andesite decreased with increasing water vapor pressure. Therefore, stress corrosion can be considered as a primary process of subcritical crack growth in andesite, and it is important to consider the effect of water vapor on the crack growth behavior. 

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